____ can determine which type of fungus is present. Since fungi generally grow slowly, it can take 2- 4 weeks for a ____ to produce test results.

dermatophyte

About 90% of fungal toenail infections are caused by a type of fungus called a ?

Fungal Cultures

A few culture mediums are available for dermatophyte growth. Sabouraud agar containing neopeptone or polypeptone agar and glucose is often used for fungal culture. However, it does not contain antibiotics and may allow overgrowth of ____ and bacterial contaminants. Mycosel, a commonly used agar, is similar to Sabouraud agar but has antibiotics. Commonly, dermatophyte test medium (DTM) is used. It contains antibacterial (ie, gentamicin, chlortetracycline) and antifungal (ie, cycloheximide) solutions in a nutrient agar base. This combination isolates dermatophytes while suppressing other fungal and bacterial species that may contaminate the cultureFollowing culture inoculation, potential fungal growth is monitored at 2 weeks and 4 weeks.Positive culture results vary depending on the medium used. DTM contains phenol red solution, which causes a color change from straw-yellow to bright-red under alkaline conditions, indicating a positive dermatophyte culture result. However, the color makes identification of culture morphology (particularly pigmentation) difficult. Sabouraud or Mycosel agar should be used to assess gross and microscopic colony characteristics.